The boys wake up excited that it's actually a Monday because it means their two months of grounding for giving away Dewey's bike to get one of Francis's friends to eat dog food is over. Lois is deathly ill, and after caring for her, Hal heads off to work and tells his sons to say goodbye to their mother before going to school. The boys go to say goodbye to Lois, and she tells them not to leave the house and not to watch TV because it's the last day of their grounding. They realize she thinks it's still Sunday, and they decide to go with it so that they don't have to go to school. They sit at home, scared to go outside and get busted for truancy, and unable to watch TV because their dad has the power cord with him and won't be plugging it back in until they get home from school.

On his way to work, Hal gets distracted by a Porsche dealership. He walks in just to look at the car, and gets pounced upon by a salesman who convinces him to look at a brochure. Then the salesman convinces Hal to take the car for a test-drive. He introduces Hal to the financing guy and the trade-in guy. Finally, he gets Hal to initial a price and works up a whole contract and payment plan. He tries to convince Hal to sign on the dotted line, but by this time Hal is freaking out and also not feeling very well. Hal fears he's come down with Lois's flu and breaks for the door, but the saleman cuts him off and convinces him to stick his head in the Porsche one more time and smell the leather and look at the console. Hal stick his head in the Porsche and throws up in it. The salesman has to drive a very ill Hal home.

Back at home, the phone rings, and the boys scramble to pick it up so that it won't wake their mother. It turns out to be Francis. Francis is scared that his mother is going to see a letter that was sent home about Francis driving a back-hoe into a swimming pool, and begs his brothers to find the letter and hide it. They do so. Then Malcolm explains their situation to Francis, and how they're bored and stuck at home. Francis tells them about an arcade downtown where the owner doesn't really stress truants. Malcolm says they have no money. Francis tells them that mom keeps money in her top left dresser drawer, and if they take between five and seven dollars, she'll never notice.

The boys sneak into their mother's room and start to open the drawer, but it squeaks and wakes her a little. She asks what they're doing, and Dewey blurts out that they're looking for money. She says she moved it to the back of the closet. Reese marvels that she moved it to where she usually hides the Christmas presents. She tells them where she moved the Christmas presents. Suddenly the boys forget all about looking for money and going to the arcade, because now they can grill their mother and finally get the truth about everything. Their final question is to ask her how they knew how Dewey's bike had disappeared, since they had lied and told her some big kid had pushed Dewey off and taken the bike. She murmurs that Francis told her.

The boys freak out. They can't believe Francis sold them out. They decide to give their mom the letter that Francis so desperately didn't want her to see. Malcolm decides to call Francis just to make sure that it wasn't just mom's delirium talking before they get Francis in trouble. Francis confirms that he ratted out his brothers and tries to explain why, but Malcolm isn't hearing it. Malcolm tells Francis they're going to give the letter to mom. The three younger brothers decide amongst themselves that they really don't want to get Francis in that much trouble, but they definitely want to taunt him with the letter and make him think that they would rat him out like he did them. Francis freaks out and calls his dead beat friends. His friends come over to get the letter from the younger brothers. Malcolm hides it in the VCR and tells Reese. Francis tells his friend Circus to watch Reese's eyes, and of course Reese entirely gives away where the letter is hidden. Francis's friends ride off on their bikes triumphant with the letter. Then Malcolm tells Reese that that was a fake letter, and he knew Francis wouldn't give up until his friends had the letter, and that Reese would give it away, so he told Reese where the fake letter was and actually gave the real letter to Dewey, which is the last thing anyone would expect. Dewey proudly announces that he hid it under mom's pillow. He did what!?

The boys go into their mother's room, but she's already found the letter. She says that she's going to send Francis away to a work camp... as soon as she's done throwing up. Malcolm calls Francis and tells him what happened. He apologizes, and swears they really had intention of actually giving mom the letter. Francis says he understands, and he's sorry about ratting them out about the bike, it was just that mom said if he told about the bike he could come home for the summer. Now his younger brothers feel really awful, and try to think of a way to save Francis's hide. Malcolm decides if they get into a whole lot of trouble, their mother will be so busy being mad at them that she won't remember to be mad at Francis. They take all their parents' prized possessions up onto the roof of the house and put them in a wheeled cart. They roll the cart off the roof into the driveway... just as the salesman is pulling up to the house in the Porsche with their very sick father. Mission accomplished.

It's night time, and the boys are still up on the roof. Lois is standing outside in her bathrobe drinking a cup of tea and telling them to come down. They say they'll come down when she tells them what she's going to do. She says she'll tell them what she's going to do when they come down. It's a stand-off.